Gallium nitride (GaN) is a desirable material for charged particle spectroscopy in high‐temperature, high‐radiation environments. We report on results obtained from GaN vertical Schottky devices fabricated on 8 µm‐thick nonintentionally doped GaN epitaxial layers grown on native GaN substrates, where the thick epilayer is intended for ionizing radiation detection. Bulk dark current densities of 2 µA/cm 2 were measured at −1 V with perimeter leakage attributed to surface effects of 4.5 nA/cm at room temperature, with an extracted Schottky barrier of 0.72 eV for a Ni/Au Schottky metal stack. The capacitance–voltage data reveal background doping in the low 10 15 cm −3 range. Pulsed 355 nm UV light produces a photoresponse that increases as a function of reverse bias, with an estimated carrier collection efficiency of up to 5%. Moving the incident beam away from the Schottky contact reveals a minority carrier diffusion length up to 10 µm, which agrees with other reports on GaN bulk diffusion lengths despite the shallow photogeneration of ∼100 nm. Finally, optical deep‐level transient spectroscopy reveals two electron trap states at 456 and 129 meV below the conduction band with low concentrations (<1% of the doping) and capture cross‐sections <10 −15 cm −2 .
Walker et al. (Fri,) studied this question.